Cement is made
from clinkers and a mix of other minerals. This production process is energy
intensive because it involves the heating of ingredients to 1,450 °C. Most of
the fossil fuels used in the industry are required for this purpose. As a
consequence, large quantities of GHG emissions are generated. The calcination reaction that takes place in cement production also
produces CO2 as an inherent process emission separate from energy
use. Therefore, part of the emissions from this sector cannot be avoided (IPCC
2014a) if the sector sticks to the conventional production processes.

In 2010, the cement industry
produced 3,551 Mt of cement. In 2050, this is expected to increase to 4,475 Mt,
an increase of almost 26 percent. Because cement is the main ingredient for
various building materials, the economic growth in developing countries (IEA
2012a)—accompanied by an increase in buildings—is expected to increase demand
for cement. This will only hold if no new building technologies or fabrications
are found with equivalent properties as a building material (e.g., steel,
glass, wood).

The cement
sector directly emitted 2.1 gigatons of CO2 in 2010. By 2050, it
would need to decrease emissions to 1.7 gigatons, a reduction of about 20
percent. Fuel-related emissions can be brought down through fuel switching, using
biofuels instead of fossil fuels, and assuming there would be sufficient access
to biofuels for the cement sector. Emissions can be brought down even further
by implementing best available technologies including energy efficiency
measures.

Energy
efficiency improvement options have limited potential because about 50 percent
of the 2010 emissions were process emissions from the calcination reaction,
which are difficult to reduce cost-effectively given current technology (IPCC
2014a). These emissions can be partially reduced by reducing the share of
clinkers or using clinker substitutes in the mix of input minerals. However,
the largest reductions in CO2 emissions from the calcination
reaction can be made by capturing and storing these emissions. By combining
these measures, the emissions per ton of cement can be brought down by around
50 percent without carbon capture and storage (CCS) and around 80 percent with
the use of CCS (IPCC
2014a).

According to
IEA, fuel switching and the use of clinker substitutes can contribute 29
percent to emission reductions in the cement sector in 2050 (+/- 265 MtCO2),
whereas CCS could be responsible for 63 percent of the emission reductions (+/-
575 MtCO2). The largest emission reduction potential is found in
India and China (IEA
2012a).

Figure I.2
shows the projected activity and emissions, and the resulting intensity pathway
for the cement sector. Emissions peak in 2020 because of the growing activity,
and then decline toward 2050 due to the effect of mitigation measures. In 2050,
emission levels will be reduced by 20 percent compared with 2010, while the
carbon intensity of cement production in 2050 decreases by 37 percent compared
with 2010.

Figure I.2 Cement manufacture
GHG emissions peak in 2020 because of activity growth, then decline toward 2050
because of mitigation measures to meet their target